Air-cooled tank engines

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The air-cooled tank engines used in the M3 Lee/Grant, M3 Stuart, and M4 Sherman tanks, as well as some post-WWII tanks are amazing to me. It seems weird that someone would come up with the idea of using a radial aircraft engine in a tank to begin with, and also that these engines were successful in this role. When I first heard that they used these radial engines, I thought that maybe they adapted them to lie flat in the rear of the tank. Nope, they were mounted upright, with a giant fan mounted to the front. Radials were used in quite a few WWII armored vehicles.

The Ford GAA, a liquid-cooled, all-aluminum, 1100 cubic-inch DOHC V8 was used in quite a few of the Shermans as well, but as tanks got heavier, starting with the M26 Pershing, it was found to be inadequate. Once again, air-cooled engines were used, starting with the Continental AV-1790 series, an air-cooled V12 (!) in both gasoline and diesel versions, producing upwards of 650 horsepower, on up to 980 or so horsepower in a gasoline version for the M51 tank retriever.

I don't know, it seems not only odd that these engines were designed as enormous air-cooled tank engines, but that they actually succeeded, and succeeded well. After all, the M60 tank used the Continental AVDS-1790-2 V12, air-cooled Twin-turbo diesel engine for its whole service life, as far as I know.
 
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Indeed and these engines ran on a mere 80 octane fuel with about a 6.5 compression ratio. With higher compression and modern fuel they could really put down some power.


Continental_AV-1790-5B.JPG
 
Don't forget the Rolls-Royce metor Tank engine.
http://en.wikipedia.org/wiki/Rolls-Royce_Meteor

basically a Merlin Aero Engine (amongst others, Spitfire, and P-51 Mustang)minus the supercharger, and some of the light weight parts replaced with heavier duty, since weight savings is not as much of a issue in a tank as a plane...)
in fact they planned on using blocks that for one reason or another didn't pass QC for merlin use.
 
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For a truly weird one, the Brits repowered many M3 (Stuart) light tanks with the Guiberson 9-cylinder, air-cooled radial DIESEL engine.
 
The Ford GAA is something else. Really a groundbreaking engine when you consider how many of the basic design elements have trickled down to automotive production engines...IE DOHC, all aluminum construction, etc.

Here's a GAA in a car (1970 Mustang)...
18rb3kvkr86ymjpg.jpg
 
Air cooled would make more sense in battle because of a loss of coolant
for whatever reason would put a liquid cooled tank engine out of
commission.

Anti-freeze would be one less thing to supply to the front.

Thanks for the topic, never much thought about it before.
 
At one point in the mid 70s GMC put Deutz air cooled diesels in medium duty trucks. The engine did a good job. The one problem that ended the experiment was lack of coolant for cab heat. Nobody built a heater core that could handle engine oil at the pressure that the engine put out. When the core failed it made an amazing mess. There would be no such problem in a military tank.
 
Originally Posted By: 01rangerxl
The Ford GAA is something else. Really a groundbreaking engine when you consider how many of the basic design elements have trickled down to automotive production engines...IE DOHC, all aluminum construction, etc.

Here's a GAA in a car (1970 Mustang)...
18rb3kvkr86ymjpg.jpg



I'm pretty sure that DOHC's and Aluminium engine components were used in auto engines long before WWII.
 
Aluminum components is an important distinction from aluminum heads/block though...and this was a V engine. Typically V engines for cars were flatheads at that time.

Dusenbergs and such were early adopters of stuff like this, but those cars had a tank price tag anyway.
 
Originally Posted By: AITG
At one point in the mid 70s GMC put Deutz air cooled diesels in medium duty trucks. The engine did a good job. The one problem that ended the experiment was lack of coolant for cab heat. Nobody built a heater core that could handle engine oil at the pressure that the engine put out. When the core failed it made an amazing mess. There would be no such problem in a military tank.


I did not know that.
 
Originally Posted By: 901Memphis
Indeed and these engines ran on a mere 80 octane fuel with about a 6.5 compression ratio. With higher compression and modern fuel they could really put down some power.


Fun factoid - many did.

Tank versions were often low octane on purpose so they could use the field-available fuel of the areas in europe they were often seeing action, but the same engines in aviation use typically had an added supercharger because they hauled in all the fuel because performance was more critical than landing and refueling in hostile territory. "Military purple" fuel had an insane amount of lead and was meant for high compression engines with high boost - octane numbers well over 100 possibly over 110 should have been the norm. (the antiknock ratings for aviation fuel doesn't directly translate to auto octane because it varied with mixture ratings and I think altitude some as well)
 
Originally Posted By: used_0il
Air cooled would make more sense in battle because of a loss of coolant
for whatever reason would put a liquid cooled tank engine out of
commission.

Anti-freeze would be one less thing to supply to the front.

Thanks for the topic, never much thought about it before.


Mixed sense - a coolant system generally shouldn't suddenly fail unless by shrapnel, but by the time the outer armor is penetrated if the crew isn't dead from the ammunition storage inside the hull cooking off or triggered by spall you probably have fuel and oil leaks too.

Air cooled engines heat up and cool down faster but a water cooled engine is capable of more 'heat soak' - you can put out more power, longer, without overheating it, which is why even some aviation warbirds were water cooled (if I remember right) for a performance combat advantage despite the lower reliability of water cooling in general.

But as of WW2 what the best formulas for anything were weren't yet known - the idea of a gasoline powered tank itself sorta went by the wayside not too long after it was seen what happens when gasoline tanks are punctured by spall. (ie the crew burning to death horrifically) Diesel is much harder to ignite and actually acts as a form of armor, even more effectively against HEAT rounds than kinetic rounds where being surrounded by diesel tanks actually is a form of additional crew protection.
 
"Mixed sense"; is my 1st thought on the topic.

I have to think of my long past family veterans of the wars and imagine what they were
confronted with and the time frame they had to react.

Sometimes its hard to imagine what they went through, and the families at home too.

In the opening of "Band of Brothers", you see Canadian artillery and a 105.

Every November 11th is not often enough.

Halifax bombers shot out of the air.

Followed by hand delivered telegrams.

That is how my "first thoughts" really look like when I don't edit them.
 
On a lighter note, I read through my late mother's diaries.

It looks like I was about 30 hours away from being born at
the Minot ND USAF base.

I don't know what she was doing down there, but she made it
back to the Canadian side and dished me out in Brandon Manitoba.

Better than on the back seat of a 51 Buick I guess.
 
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Originally Posted By: 74DartSport
Let's not forget the eggbeater.


Which eggbeater is that?

I also respect the crews who were able to keep these monstrosities running - and yank them out and replace them when it became necessary.
 
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